SIG SAUER – MCX Mandatory Carriage Assembly Replacement Program

Sig Sauer website
Sig Sauer website
Sig Sauer

Newington, N.H. -( SIG SAUER is conducting a mandatory replacement of the carriage assembly in SIG MCX rifles.

SIG has found through extensive factory testing that in extremely rare instances, not reported in the field and extremely difficult to replicate, a condition may exist causing an unintended discharge.

Failure to follow the loading procedures and basic rules of safe firearms handling outlined in the user’s manual has the potential to cause serious bodily harm or death.

Although this has only been witnessed in 300 blackout, SIG has decided to upgrade all MCX models since the MCX is a modular platform and we want to ensure the quality and reliability of all products we manufacture.

Stop use of firearm immediately, and visit the SIG SAUER website listed below as soon as possible to register your firearm, initiate the process and view a video explaining how to change out your carriage assembly.

SIG will send you a prepaid box to return your complete carriage assembly to the factory. A new assembly, designed with the firing pin locking mechanism, will be shipped out to you within 5-7 working days of the receipt of your parts at no cost to you. Please note total in transit times will vary based on geographic locations.

SIG will also send you a $50 gift voucher for any inconvenience this may have caused. This upgraded carriage assembly addresses this potential issue while enhancing the performance and longevity of your rifle.

You may also contact SIG SAUER customer service at the number below with any questions if needed. SIG SAUER is committed to addressing this issue in an expedited manner, and appreciates your support.

Firearm Registration –
For Customer Service – 603-610-3000: Option 1
For Instructional Video –

*Serial numbers 63C000044 – 63C003702 – Contact SIG Customer Service for instructions.

*If you have replaced your trigger group with an aftermarket trigger please contact SIG Customer Service for instructions.

*SIG SAUER Dealers should call designated Commercial Sales Support Representative.

*Any MCX rifle with a serial number ending in 25000 or higher is exempt from this program.

Current Carriage Assembly

Current Sig Sauer Carriage Assembly
Current Sig Sauer Carriage Assembly

NEW Carriage Assembly with Firing Pin Lock

NEW Sig Sauer Carriage Assembly with Firing Pin Lock
NEW Sig Sauer Carriage Assembly with Firing Pin Lock


About SIG SAUER, Inc.:

SIG SAUER, Inc. is The Complete Systems Provider™, leading the industry in American innovation, ingenuity, and manufacturing. SIG SAUER® brings a dedication to superior quality, ultimate reliability, and unmatched performance that has made it the brand of choice among responsible citizens, and many of the world’s most elite military, government, and law enforcement units. SIG SAUER offers a full array of products and services to meet any mission parameter, including handguns, rifles, ammunition, optics, suppressors, ASP (Advanced Sport Pellet) airguns and training. The largest member of a worldwide business group of firearms manufacturers that includes SIG SAUER GmbH & Co. KG in Germany and Swiss Arms AG in Switzerland, SIG SAUER is an ISO 9001: 2008 certified company with more than 1,400 employees.

For more information on SIG SAUER, any of its products, or the SIG SAUER AcademySM log on to their website.

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It is NOT an issue…you can still take it fully apart, I just did it…just have to depress the firing pin rod, then bingo…comon give Sig credit, they are a classy outfit


How did you figure is impossible to disassemble? You can remove firing pin also op rod only spring plate is no removable, that prevent spring to go to shit ! I seen spring tangled and jammed ammo, then need replace both springs this should fix problem with springs!

Jim in Conroe

The firing pin retaining pin is labeled as “non removable.” If you can’t remove the retaining pin, you can’t remove the firing pin. If you can’t remove the firing pin, you can’t remove the pin that holds the bolt, which means you can’t remove the bolt.

Mark Brockway

I have no plans to do this silly “upgrade.”

Jim in Conroe

This upgrade appears to make it impossible to disassemble, clean, and lubricate the bolt carrier group or replace the firing pin. I don’t see how this improves reliability for a problem that has never been observed in the field and is difficult to replicate in the lab. Furthermore, as long as you observe safe firearms handling practices, the problem of an accidental discharge is stated not to be a problem at all.

If I had one of these rifles, I would seriously consider staying with the unmodified version.